These factors expressed at the surface of the bacteria comprise the M proteins (124 serotypes), the hyaluronic acid capsule, and fibronectin-binding proteins, and other factors (lipoteichoic acid, various proteins) which allow
S. pyogenes to bind to, colonize, and invade human mucus tissues and skin.[1,2] M proteins are the major virulence factors of the microorganism and act as antiphagocytic effectors by interfering with opsonization and phagocytosis by polymophonuclear leucocytes via the alternate complement pathway. Strains of certain GAS M-protein types are more often associated with particular severe clinical syndromes. For example, during the past two decades, strains of M1 and M3 types have been frequently isolated from patients with severe invasive diseases associated with increased mortality in North America and Europe.[1,4,8] The resurgence of ARF in the 1980s in the United States was strongly associated with type M18 strains.
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The use of dumbbells gives you a much more comprehensive strengthening effect because the workout engages your stabilizer muscles, in addition to the muscle you may be pin-pointing. Without all of the belts and artificial stabilizers of a machine, you also engage your core muscles, which are your body's natural stabilizers.